Buggy code:
public abstract class PhysicalTraitsPlayerData extends GoreCorePlayerData implements PhysicalTraitsStatisticsRecorder { private double weight ; private boolean weightRecentlyChanged ; private double weightChangeTicks ; private double energy ; private int energyUseTicks ; private double fatigue ; private int fatigueRegenTimeout ; private double strength ; private boolean strengthRecentlyChanged ; private double height ; private boolean heightRecentlyChanged ; private double endurance ; private boolean enduranceRecentlyChanged ; private int prevHunger ; public PhysicalTraitsPlayerData ( GoreCoreDataSaver dataSaver , UUID playerID ) { } @ Override protected void readPlayerDataFromNBT ( NBTTagCompound nbt ) { } @ Override protected void writePlayerDataToNBT ( NBTTagCompound nbt ) { } @ Override public final double getWeight ( ) { } @ Override public final void setWeight ( double weight ) { } @ Override public final void gainWeight ( double weight ) { } @ Override public final void loseWeight ( double weight ) { } @ Override public final boolean weightRecentlyChanged ( ) { } @ Override public final void noteWeightChanged ( ) { } @ Override public final double getEnergy ( ) { } @ Override public final void setEnergy ( double energy ) { } @ Override public final void energize ( double energy ) { } @ Override public final void tire ( double energy ) { } public final void adjustEnergyAndWeight ( ) { } public final void useEnergy ( FoodStats fs ) { } public final void updateEndurance ( EntityPlayer player ) { if ( GoreCoreIsPlayerWalking . isWalkingStatic ( player ) ) { gainEndurance ( configuration . setting_enduranceWalking ( ) ) ; } else if ( player . isSprinting ( ) ) { gainEndurance ( configuration . setting_enduranceSprinting ( ) ) ; } else { <START_BUG> loseEndurance ( configuration . setting_enduranceLoss ( $missing$ ( ) ) ) ; <END_BUG> } } @ Override public final double getFatigue ( ) { } @ Override public final void setFatigue ( double fatigue ) { } @ Override public final void exhaust ( double fatigue ) { } @ Override public final void recover ( double fatigue ) { } @ Override public final void resetFatigueRegen ( ) { } @ Override public final boolean tickFatigueRegen ( ) { } @ Override public final double getStrength ( ) { } @ Override public final void setStrength ( double strength ) { } @ Override public final boolean strengthRecentlyChanged ( ) { } @ Override public final void noteStrengthChanged ( ) { } @ Override public final void strengthen ( double strength ) { } @ Override public final void weaken ( double strength ) { } @ Override public final double getStrengthPercent ( ) { } @ Override public final void setStrengthPercent ( double strength ) { } public final double getHeight ( ) { } public final void setHeight ( double height ) { } @ Override public final void heighten ( double height ) { } @ Override public final void shorten ( double height ) { } @ Override public final boolean heightRecentlyChanged ( ) { } @ Override public final void noteHeightChanged ( ) { } @ Override public double getEndurance ( ) { } @ Override public void setEndurance ( double endurance ) { } @ Override public void gainEndurance ( double endurance ) { } @ Override public void loseEndurance ( double endurance ) { } @ Override public boolean enduranceRecentlyChanged ( ) { } @ Override public void noteEnduranceChanged ( ) { } }

Fix:
loseEndurance ( configuration . setting_enduranceLoss ( ) ) ;